FIELD OF THE INVENTION
The invention relates to a method for determining a rotational speed for an idling control of an internal combustion engine, in particular of a diesel internal combustion engine with an idling controller.
Critical operating ranges of a diesel internal combustion engine are idling and low partial load. Although consumption values are very favorable in that operating range in comparison with a spark ignition engine, in modern diesel internal combustion engines the idling speed is reduced further for reasons of economy. However, since there is an increase in idling noises, in particular so-called knocking as the idling speed decreases, and there is a risk of the internal combustion engine stalling at an excessively low rotational speed, precise determination of the rotational speed is becoming increasingly significant for idling control.
German Patent DE 36 09 245 C2 discloses a device for controlling the idling speed of a multi-cylinder internal combustion engine, in particular a diesel internal combustion engine with a proportional-integral-differential controller (PID controller), in which device an average rotational speed and a cylinder-specific rotational speed are measured and evaluated using marks on the crankshaft. An individual cylinder control is used to carry out a fuel correction as a function of those measurements by changing control constants of the PID controller so that the smoothness of the running is improved.